Lew's job isn't quite as perilous as the one that greeted the now-departed Timothy Geithner four years ago. As Treasury secretary, Geithner had to help stabilize a teetering U.S. banking system after the worst financial crisis since the 1930s and help lift the economy out of a deep recession.

The economy and banking system are far healthier now. But if the Senate backs Lew's nomination after a committee hearing Wednesday, he will likely have to marshal all his strengths as a budget specialist and perhaps overcome inexperience in some areas to achieve significant success.

The federal budget is sure to preoccupy Lew's early weeks, and it's also likely to dominate his confirmation hearing before the Senate Finance Committee. Republicans are expected to use the hearing to stress their differences with the administration over deficits and taxes.

Sen. Orrin Hatch of Utah, the panel's top Republican, said he would press Lew on "what kind of plan the Obama administration has to confront our skyrocketing debt and our broken entitlement programs."

Lew, 57, will likely be well-prepared to spar over taxes and spending. He has twice served as a White House budget director — once during the Clinton administration and once under Obama before becoming White House chief of staff.

Going back to his days as an aide to House Speaker Tip O'Neill in the early 1980s, Lew has amassed three decades of experience at the top levels of Washington policy-making.

He isn't expected to have trouble winning Senate confirmation, despite the likely arguments from Republicans that the administration isn't doing enough to contain "entitlement" programs such as Medicare, Medicaid and Social Security whose costs are straining the federal budget.

After Wednesday's hearing, committee members will have two days to send questions to Lew to answer before they vote. The full Senate could vote on the nomination late this month.

That would give Lew little time before his first budget challenge — the March 1 date when deep spending cuts in defense and domestic programs will kick in unless Congress and the administration agree on some way to avert them.

The second challenge would come March 27, when much of the government would shut down if Congress doesn't extend a temporary measure authorizing funding. And the nation's borrowing limit must be raised by May 18 or the government could default on its debts.